Technical Field
The present disclosure relates to a nitride semiconductor element that is formed by crystal growth from a substrate, and a method for manufacturing the same.
Description of the Related Art
A light emitting diode (LED) made of a nitride semiconductor is normally formed by sequentially stacking an n-type semiconductor layer, an active layer and a p-type semiconductor layer on a sapphire substrate. Conventionally, there has been proposed a technique which involves providing a structure with elongated recess portions or a composite structure with elongated projection and recess portions at a sapphire substrate in advance in order to improve the light emission efficiency of a light emitting diode (see, for example, JP 2008-53385 A, JP 2008-91942 A, and JP 2012-114204 A).
The sapphire substrate with elongated trenches (i.e. recess portions) mentioned above has a certain effect of reducing a dislocation density. However, if timing of crystal growth differs between the bottom surface of the trench and an upper surface of the sapphire substrate having no trench, the crystallinity would become deteriorated.